The invention relates to a method for printing continuous forms, according to which one brings a strip to be printed, which is provided adjacent both lengthwise edges thereof with round perforations, between a printing cylinder and a counter-pressure cylinder cooperating therewith of an offset printing mechanism which perform simultaneously, per printing operation, a revolution in opposite direction and which during a simultaneous revolution, firmly clamp the strip over part of said revolution and notably during the printing operation proper, and feed same forwards, and over another part of the revolution, release the strip, and during the release of said strip, by means of at least one pair of pin tractors, one of which is arranged respectively on both edges and which are provided with pins the base diameter of which is smaller than the diameter of the round perforations in said strip, one moves said strip backwards over a distance which is substantially equal to the difference between the forward displacement during said revolution and the length of a form to be printed.
With such a method, forms with various lengths may be printed.
In known methods of this kind, the printing is however inaccurate. The perforations in a strip of paper always are of necessity of a larger diameter than the pin base of the pin tractors, whereby the accurate positioning of the strip, immediately before being clamped between the printing cylinder and the counter-pressure cylinder is not possible.
Due to the strip of paper being moved backwards by the pins, said pins always come to lie against the perforation back, whereby thus when the strip is clamped back between the printing cylinder and the counterpressure cylinder, the pins can not drive the strip directly forward.